BE35 pilot reports critical conflict with B757 at 7500 feet west of ord class B.

Attributes
ACN	806419
Time
Date	200809
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : arr.airport
State Reference	IL
Altitude	msl single value : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Bonanza 35
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	None
Aircraft 2
Controlling Facilities	tracon : ord.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : atp pilot : cfi technician : airframe technician : powerplant technician : inspection authority
Experience	controller non radar : 35 controller radar : 25 flight time last 90 days : 150 flight time total : 18000 flight time type : 30
ASRS Report	806419
Events
Anomaly	conflict : airborne critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure
Primary Problem	Flight Crew Human Performance

Narrative:

I was alone in cruise (heading 010 degrees) on my way to brookfield wi at 7500 ft MSL just west of ord class B airspace when I noticed what appeared to be a B757 headed straight toward me at the same altitude. I immediately descended and reduced power thereby allowing the aircraft to pass overhead with approximately 500 ft vertical margin. My transponder was operating in mode C and squawking 1200. I had been in contact with another ATC facility earlier in the day and experienced no equipment malfunctions that would render me invisible to ATC or other traffic. I noticed no evasive action on the part of the oncoming jet; so I'm not sure they saw me.

Original NASA ASRS Text

Title: BE35 PILOT REPORTS CRITICAL CONFLICT WITH B757 AT 7500 FEET WEST OF ORD CLASS B.

Narrative: I WAS ALONE IN CRUISE (HDG 010 DEGS) ON MY WAY TO BROOKFIELD WI AT 7500 FT MSL JUST W OF ORD CLASS B AIRSPACE WHEN I NOTICED WHAT APPEARED TO BE A B757 HEADED STRAIGHT TOWARD ME AT THE SAME ALT. I IMMEDIATELY DSNDED AND REDUCED PWR THEREBY ALLOWING THE ACFT TO PASS OVERHEAD WITH APPROX 500 FT VERT MARGIN. MY XPONDER WAS OPERATING IN MODE C AND SQUAWKING 1200. I HAD BEEN IN CONTACT WITH ANOTHER ATC FACILITY EARLIER IN THE DAY AND EXPERIENCED NO EQUIP MALFUNCTIONS THAT WOULD RENDER ME INVISIBLE TO ATC OR OTHER TFC. I NOTICED NO EVASIVE ACTION ON THE PART OF THE ONCOMING JET; SO I'M NOT SURE THEY SAW ME.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.